Field of the invention
The present invention relates generally to a safety release assembly,
and more specifically to an safety release mechanism which is designed for use
with climate chambers, or the like.
A safety release mechanism for the doors of freight containers is
shown in GB A 2 154 646. Said mechanism comprises a lever for rotating an operating
bar which is equipped with locking cams. Said lever is in locked condition secured
to a retainer, which in turn, is held fast with the door by permanent fixings.
The emergency release mechanism provides releasable fixings for the retainer, which
can be released from the inside by turning pins. By pushing a plunger assembly,
the door is opened. This action urges the unfastened retainer outward from the door,
carrying with it the operating lever. The plunger assembly rotates the operating
lever and hence the operating rod during actuation.
GB 1 490 651 discloses a door lock and safety release mechanism of
a type where the locking mechanism is a rotatable locking bar, which when rotated
engage separate keeper members. The rotation is effected by turning a hand lever,
which, when the locking bar has been rotated into engagement with the keeper members
is held by retainer means. Said retainer means comprises a hub, which is held in
the door by a threaded rod screwed into said door. Said rod extends though the
door, on the inside of which is found the safety release mechanism. On the inside
of the door is arranged a rotatable mechanism, by means of which the threaded rod
can be unscrewed from its engagement with the door, which in turns has the effect
that the hub, holding the retainer means assembly, is pushed in an outward direction
in relation to the door, thereby also pushing the hand lever in the same direction.
Since the hand lever is connected to the locking bar, the outward movement of the
hand lever causes the locking bar to rotate, which rotation disengages the radially
extending portions of the locking bar from the keeper members.
Another safety opening device is disclosed in EP A 0 580 911, in which
the portion of the door onto which the locking member, padlock or the like is attached,
is removable by releasing a mechanism which locks said door portion, and subsequently
pushing said door portion outwardly, thereby achieving the effect of also pushing
aside and turning into open position the locking mechanism of the door to be locked.
Finally, US 2 636 767 discloses a mechanism, which functions in a
manner which is parallel to the mode of function of GB A 2 154 646, i.e. that a
retaining element which is screwed to the door may be unscrewed from the inside.
The solutions for a safety release mechanism in the above cited document
have, however, some serious drawbacks in relation to climate chambers, and other
highly corrosive environments. The number of parts, and accordingly, the number
and the size of the surfaces which are exposed to the corrosive climate, is very
high. It is in many cases possible to manufacture the exposed parts in a material
which is able to withstand corrosion, although at a very high cost. In a climate
chamber for drying wood such as planks, boards and the like, the only acceptable
materials are pure aluminium and stainless steel.
Another salient problem is the sealing of all openings, the most important
being the opening through the door, which houses parts of the safety release mechanism.
If the corrosive climate is allowed to leak though an opening in the door, parts
arranged on the outer side of the door may be affected by this, causing corrosion
to vital parts, and maybe even the door itself, which is, of course, is very costly.
Further, such leakage is of course influencing the power consumption of climate
control devices inside such chambers. This constitutes a serious problem for the
above cited devices.
Another desired characteristic feature is easy actuation of the safety
release mechanism. Most prior art devices require that a threaded rod or the like
need to be unscrewed from the inside, before the door may be opened. After use
of the safety release mechanism, it has to be refitted, i.e. screwed back in place,
Yet another desired characteristic is the possibility of using such
a device with a door which previously lacked a safety release mechanism.
There is, then, a need for a safety release mechanism, which may be
manufactured in materials resistant to corrosion at a low cost, which safety release
mechanism is arranged in such a way as to completely seal off the climate within
the room to which the door leads, and which is easy to actuate, may be returned
to locking position with the same ease, and which is, finally, easy to fit in a
door which previously lacked a safety release mechanism.
Summary of the invention
The drawbacks of prior art devices are overcome by the safety mechanism
according to the invention, by providing, on the inside of the door, a lever and
a simple releasable lever retaining device, which allows locking of a door from
the outside only when the retainer device is in its locking mode. When the retaining
device is released, and the lever is removed from its retained position, it is
impossible to lock the door from the outside. If, inadvertently, the door was locked
from the outside, i.e. with the safety mechanism activated, the lock is rendered
inoperative simply by raising said lever, and the door may be opened from the inside.
The inventive safety mechanism is defined in claim 1.
Preferred embodiments of the invention are defined in the dependent
Short description of the drawings
The invention will be described in closer detail in the description
which follows, reference being made to the accompanying drawings, in which
Detailed description of the invention
- fig. 1 is an exploded view of a safety release assembly according to an embodiment
of the present invention,
- fig. 2 is a plan view of the details of a safety release assembly according
to an embodiment of the present invention, located on the outside of a door,
- fig. 3 is a plan view, from above, of a conventional locking mechanism,
- fig. 4 is a plan view of the details of a safety release assembly, according
to an embodiment of the invention, which are located on the inside of the door,
- fig. 4a is a perspective view of details in fig. 3.
Fig. 1 shows an exploded view of a safety release assembly according
to the present invention. The assembly comprises a connecting rod 1 of tubular
shape, which is rotatably mounted in a hole 2 in a door D which is to be locked.
The connecting rod 1 has a locking bracket 4 attached to a first end thereof, which
locking bracket 4 has a forward portion with the general shape of a "T" in plan
view (the shape can be seen in fig. 2), and has a slot 4b for receiving a locking
arm. The second end of the connecting rod is adapted for pivotable attachment to
an actuating arm 5, e.g. by means of a locking screw (not shown) in a hole 3. The
actuating arm 5 is comprised of a tubular rod, to a first end of which is attached,
e.g. by means of welding in the case of a metallic material, two parallel flanges
6 having cam surfaces 6a and mutually concentric holes 6b, for receiving the above
mentioned locking screw which pivotably joins the connecting rod 1 and the actuating
arm 5, thus enabling the actuating arm 5 to be moved between a first, or retaining
position, and a second position in which it is freely movable. The second end of
the tubular rod 5, as well as the end of the connecting rod which is located on
the inside of the door, may advantageously be sealed by appropriate means, such
as an end hat. Said second end of the actuating arm 5 is, in the retaining position
received by retaining means 7, pivotably mounted to door D, as shown in the figure
1, and designed so as to prevent movement of the arm 5 in retaining position. Retaining
means 7 comprise a bracket 8, having the general shape of a "U" (see fig. 4a),
which is pivotable around pivots 8a, and has a handle knob 7b affixed thereto for
ease of actuation of retainer means 7 by a user. Retaining means 7 is provided
with means for adjustably applying a desired bias force to the actuating arm 5,
as will be explained below.
In a preferred embodiment there is also provided a mount 1a for the
connecting rod, in order to ensure that the locking bracket 4 is positioned at
a suitable distance from the door, a distance which depends on the individual door,
and for receiving the load which is applied to the assembly of the connecting rod
1 and the mount, especially in the case of a door with a soft insulation material,
such as mineral wool or the like, which would otherwise be deformed. This bias
forced is applied in order to compress into a sealing condition, at least one sealing
member 1b, which is arranged on the inner surface of the door. In operating mode,
as will be explained below, the sealing member is compressed by the cam surfaces
6a of the actuating lever 5 acting on a washer 1c which is placed between the sealing
member 1b and the cam surfaces, in order to achieve a good sealing. The sealing
member 1b is preferably made of a material with high sealing and wear capability,
such as silicone.
Figure 2 shows a locking arm 9, preferably pivotable in the horizontal
and the vertical directions, which is connected to a locking rod 11, which connects
the locking arm 9 to a conventional locking mechanism, which is described further
below, together with fig. 3. The locking bracket 4 has a slot 4b (see fig. 1) for
receiving the locking arm 9. As can be seen from fig. 2, the locking arm 9 also
has a hole 9a for receiving a locking device (not shown), which may be a padlock
or the like. In order to provide the mechanism with a locking function, the locking
bracket 4 has, as was mentioned above, the general shape of a "T", where the upper,
horizontal bar of the "T" constitutes a locking flange arm 4b, which can co-operate
with the locking device.
The above mentioned conventional locking mechanism comprises hook-shaped
locking members 10, extending radially from the locking rod 11. On the doorframe
or other part of the structure in which the door is arranged, there are provided
arch-shaped members 12, which are engagable by the hook-shaped locking members
10, when the locking rod 11 is rotated by moving the locking arm 9 (fig. 2) in
an inward direction,
Figure 4 shows the details of the inventive assembly from the inside.
The lever retaining means 7 is shown in a retaining position, in which it retains
the actuating lever 5, which is received within a bracket of the retaining means
7. The bracket, together with other details of the construction of the retaining
means, is shown in perspective in fig. 4a. Said bracket 8, has mounted onto it
a spherical handle knob 7b, which knob is gripped by a user when he or she wishes
to operate the retaining means 7 in order to release the actuating arm 5. Adjustment
means 7a (see fig. 1) is provided for adjusting the bias of the sealing member,
as will be explained below.
In use, the inventive safety release assembly is set in operating
mode by turning the locking bracket 4 into a position in which it can receive the
locking arm 9. This is done by rotating the connecting rod 1, onto which the locking
bracket 4 is fixed, preferably by welding, by gripping and turning the actuating
lever 5. The locking bracket 4 is in receiving position on the outside of the door
D when the actuating lever may be pivoted towards the door D and be received within
the bracket 8 of the retaining means 7. The retaining means 7 is pivoted away from
the actuating lever 5, the actuating lever 5 is pivoted towards the door D, whereby
it is received within the bracket 8 of the retaining means 7 when said means 7
are pivoted back to the position which is shown in figure 3.
When the actuating lever 5 is pivoted towards the door D, the cam
surfaces 6a will eventually come to abut against the washer 1c, which is placed
on top of the sealing member 1b. When the actuating lever 5 is pushed further,
the cam surfaces 6a will act upon the washer 1c, and consequently the sealing member
1b, which preferably is of a shape which corresponds to the shape of the washer
1c. The sealing member 1b is thus compressed into a condition where it seals the
connecting rod 1 penetration passage 2 through the door. In case that the sealing
member 1b should be worn, it might be necessary to retain the actuating arm 5 in
a position closer to the inside of the door, in order to achieve the desired compression
of the sealing member 1b. For this case, the retaining means is provided with adjusting
means 7a, e.g. an adjusting screw (see fig. 1), by means of which this may be achieved.
In a preferred embodiment of the invention, the connecting rod 1 penetrates
the door D though a mount 1a with the form of a tube, which is flush with the inner
surface of the door, and protrudes a predetermined distance on the outside of the
door, said distance being determined for each individual door. This door mount
1a performs two functions. Firstly, by protruding a distance outwards from the
surface of the door D, it keeps the locking bracket 4, at a predetermined distance
from the door D, since the locking bracket 4 will abut against the end of said
mount 1a. Secondly, since the locking bracket 4 abuts against the end of the mount
1a, it will serve to receive the force which is applied to the connecting rod 1,
and thus the locking bracket 4, on the outside of the door, and to the surface
of the door on the inside. This is important in the case of a door which comprises
a thin sheet material, such as aluminium or stainless steel, and a soft insulation
layer, such as mineral wool, or the like. In this case, the door will not be able
to take up the load without deforming; therefore, the mount 1a is indispensable
for doors thus constructed.
When the inventive safety release assembly is in operating mode, the
doors D is shut, and locked by pushing the locking arm 9 towards the door D, which
brings the hook-shaped locking members 10 into engagement with the respective arch-shaped
members 12. The locking arm 9 is then inserted into the slot 4a in the locking
bracket 4 and is thus secured in a locked position. An appropriate locking device,
e.g. a padlock may then be inserted into the hole 9a in the locking arm 9, in order
to prevent unauthorised access to the space inside of the door D, by simply lifting
and pushing outwards the locking arm 9.
If, however, a person is inside said space when the door is locked
from the outside, the door D may be opened from the inside by means of the inventive
safety release assembly. This is done by pushing the actuating rod 5 towards the
door D, thereby releasing the outwardly directed force which acts upon the retaining
means 7, which force results from the bias force applied on the connecting rod
1. After this force on the retaining means 7 is released, said retaining means
7 is pivoted in a direction away from the actuating rod 5, thereby releasing said
actuating rod 5 from the retained position, to a second position, in which it is
freely movable. The actuating rod 5 is then used to rotate the connecting rod 1,
and thus the locking bracket 4 such, that the flange arm 4a, which prevents the
locking arm 9 from being lifted up from the slot 4b, by obstructing the upward
movement of the locking device, will be brought out of the position in which it
is able to obstruct the upward movement of the locking arm 9. When the connecting
rod 1 and the locking bracket 4 have been rotated 180°, no part of the locking
bracket 4 is able to obstruct the movement, in any direction, of the locking arm
9. This means that the door D is openable from the inside, simply by pushing the
door D outwards, whereby the hook-shaped locking members 10 are urged to rotate
around the arch-shaped members 12. This rotation is possible since the locking
arm 9, which is fixedly connected thereto, no longer is prevented from moving,
and the locking members 10 will eventually disengage from the members 12. Said
disengagement means that the door D is free to be pushed open from the inside.
The described embodiment of the present invention described above
is intended for use with rooms with a relatively high temperature and humidity.
All the parts of the safety release mechanism are, in order to withstand that highly
corrosive environment, manufactured from a corrosion resistant material, such as
pure aluminium, or stainless steel. The penetration passage 2 between the insulated
climate inside the room, which may contain oxidative pollutants or the like, and
the ambient atmosphere may be sealed by means of further sealing members.
In an alternative embodiment of the invention, the safety release
mechanism is adapted for use in cold storage facilities. In order to prevent the
leakage of cold out of the room, the connecting rod 1 may be formed from two separate
end portions, interconnected by means of a similarly shaped central connecting
portion, in a plastic material, such as PTFE (polytetrafluoroethylene), or the
like, with low thermal conductivity. Yet another possibility consists in manufacturing
the connecting rod in one piece from a material such as PTFE, although this reduces
the resistance to wear.
The invention has been described in relation to specific embodiments.
For instance, the padlock may be substituted by a conventional lock, or any other
means which are capable of performing the same function. As a further example,
the retaining means could have any structure which permits releasable retaining
of the actuating arm, and adjustment of the load in retaining, or locking position.
The invention is, however, not limited by such detail. A great number of alternatives
and modifications are conceivable, without departing from the scope of the present
invention, which is defined, solely, by the appended claims.